Bismuth titanate pyrochlores doped by alkaline earth elements: First-principles calculations and...
Krasnov, A.G.; Shein, I.R.; Piir, I.V.; Ryabkov, Y.I.
2018-04-01 00:00:00
Combined ab initio and experimental study of Mg-, Ca-, Sr-, Ba-doped bismuth titanate pyrochlores (BTO) has been carried out. It is revealed that the substitution of bismuth atoms by alkaline earth elements is a preferable process rather than the substitution of titanium atoms according to the structural and energy parameters from the first-principles calculations. The pyrochlore-type compounds Bi1.5Mg(Ca)xTi2O7-δ have been obtained at x = 0.25. Bismuth titanate pyrochlores doped with Mg and Ca are wide-band semiconductor materials with the maximum of light absorption at wavelengths <450 nm. The impedance study of new pyrochlore compound Bi1.5Ca0.25Ti2O7-δ was carried out. Ca-doped BTO is a mixed electronic-ionic conductor with the activation energy of bulk conductivity about 1.00 eV in the temperature range 200–750 °C.
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Abstract

Combined ab initio and experimental study of Mg-, Ca-, Sr-, Ba-doped bismuth titanate pyrochlores (BTO) has been carried out. It is revealed that the substitution of bismuth atoms by alkaline earth elements is a preferable process rather than the substitution of titanium atoms according to the structural and energy parameters from the first-principles calculations. The pyrochlore-type compounds Bi1.5Mg(Ca)xTi2O7-δ have been obtained at x = 0.25. Bismuth titanate pyrochlores doped with Mg and Ca are wide-band semiconductor materials with the maximum of light absorption at wavelengths <450 nm. The impedance study of new pyrochlore compound Bi1.5Ca0.25Ti2O7-δ was carried out. Ca-doped BTO is a mixed electronic-ionic conductor with the activation energy of bulk conductivity about 1.00 eV in the temperature range 200–750 °C.

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